2003 Cadillac Deville OIL LEAK

The shocks should not have leaked that much. The load leveling system, which only applies to the rear has no fluid other than the shocks themselves. Did the fluid have a color? By the front of the engine, are you talking the front of the car, or rh(pass.) Side.
A few possibilities are the a/c compressor(clear oil/iridescent green if dye is present), power steering(off clear to brown and you would have noise), engine oil from lower crankcase or timing cover, brake fluid(you would have spongy pedal/pulling, and red brake light). The front engine mount(in center front of car) is liquid filled with a dark brown fluid, if it is split you will have a clunk on acceleration from a stop.

From my experience, kitty litter was good with oils, it was water based liquids that didn't absorb. We use a commercial oil absorbent for oils that is litter without the perfumes. Something should be noticed as low, at least the vitals that you can check. A color would really be helpful. If you can, park it over a piece of cardboard, or white paper, and see if that helps. Otherwise, check the fluids(trans, oil, coolant, brake, and power steering), and verify that they all are full. Monitor from a full point and see which one is losing liquid. I'm a technician at a Cadillac dealer, and can say that anything has a potential to leak. The coolant can be kind of oily depending on the concentration, it will be pink. You have level monitoring on engine oil, coolant, and brake fluid, that will give you a warning on the dash. The other fluids won't, they need physically checked.